Clutch cover assembly

ABSTRACT

A clutch cover assembly, in which a radially inner side spring force action point (an inside projection 44, for example) of a lever 40 is provided at a position radially inward from an outer peripheral edge 33 of a diaphragm spring 30. A radially outer side spring force action point (an outside projection 46) of the lever 40 is positioned at a distance B between a rotation center O1 of the lever 40 and the outer side spring force action point shorter than a distance A between the rotation center O1 and the inner side spring force action point. The lever 40 is adapted to multiply a spring force P of the diaghragm spring 30. 
     The reaction force action point of the diaphragm spring 30 is shifted to an outer peripheral part of the clutch cover 16, so that a deflection of the clutch cover 16 is reduced and a release efficiency is improved.

INDUSTRIAL USEFUL FIELD

This invention relates to a clutch cover assembly, in which a springmember for pressing a pressure plate is disposed at an outside of aclutch cover.

BACKGROUND ART

A conventional arrangement of this type of clutch is illustrated in FIG.3 (Published Patent Application (KOKAI) No. 57-79331).

In FIG. 3, 10 is a flywheel of an engine. A clutch disc 14 is sandwichedbetween the flywheel 10 and a pressure plate 12. The pressure plate 12is covered by a clutch cover 16. A spring member 18, formed into anannular disc shape, and a release operation lever 20, transmitting aspring force of the spring member 18 go the pressure plate 12, aredisposed at an outside of the clutch cover 16. The lever 20 is disposedat four places, for example, in a circumferential direction of theclutch with equal distances left therebetween and is so constructed thanan inner peripheral side end of the lever 20 is pressed by a releasebearing 24 concentric with an input shaft 22.

However, the conventional embodiment of FIG. 3 includes a problem thatthe spring member 18 is supported by an inner peripheral part of theclutch cover 16. The clutch cover 16 tends to be distorted by a reactionforce of the spring member 18 to cause a decrease in a displacement of atip end of the lever 20. The ratio of displacement of the pressure plate2 to that of the lever 20, i.e. a release efficiency is deteriorated.

Furthermore, multiplication of the spring force of the spring member 18is limited because a lever ratio of the lever 20 is small.

Furthermore, the axial dimension of the entire clutch becomes largebecause the spring member 18 and the lever 20 are disposed in series inan axial direction of the clutch.

DISCLOSURE OF THE INVENTION

An object of the invention is to provide a clutch cover assembly, inwhich an annular disc-like spring member is disposed at an outside of aclutch cover, characterized by that a release efficiency can beimproved, a lever ratio for multiplying a spring force of the springmember can be set large and an axial dimension of the assembly can beshortened.

Other features and advantages of the invention will become apparent fromthe description given below, taken in connection with the accompanyingdrawings.

STRUCTURE OF THE INVENTION

(1) Technical measure

This invention provides a clutch cover assembly, in which anapproximately annular disc-like spring member is disposed at an outsideof a clutch cover covering a pressure plate and is adapted to press onthe pressure plate; characterized by that the spring member is composedof a diaphragm spring exerting its spring force in a direction oppositeto the pressure plate; the clutch cover supports an outer peripheralpart of the diaphragm spring and forms a fulcrum for stopping thereaction spring force of the diaphragm spring; a lever for multiplyingthe spring force carried by the clutch cover around a rotation center islocated at a position radially inner than a spring force transmittingpart of the pressure plate, and is disposed in a radial direction; aradially inner side spring force action point of the lever is providedat a position radially inner than said fulcrum of the diaphragm spring;a radially outer side spring force action point of the lever is providedat a position to cause a distance between the rotation center of thelever and the outer side spring force action point to be shorter than adistance between said rotation center and the inner side spring forceaction point; and the lever is adapted to multiply the spring force ofthe diaphragm spring.

(2) Function

Because the reaction force of the diaphragm spring is carried by theouter peripheral part, the action point of reaction force is positionedat the outer peripheral part of the clutch cover. The deflection of theclutch cover is reduced and release efficiency is improved.

It becomes possible to set a layer ratio of the lever.

The lever is required only to transmit the spring force of the diaphragmspring to the pressure plate while multiplying the force. It becomespossible to set the lever ratio large and to shorten the axial dimensionof the clutch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional partial view of a clutch of a firstembodiment according to the invention.

FIG. 2 is a vertial sectional partial view of a second embodiment.

FIG. 2a is an enlarged view of the part in the circle "a" FIG. 2.

FIG. 2b is an enlarged view of the part in the circle "b" FIG. 2.

FIG. 3 is a vertical sectional view of a conventional arrangement.

BEST MODE FOR CARRYING OUT THE INVENTION

(1) First embodiment

In FIG. 1, which is a vertical sectional partial view of a clutch forlarge automobile according to the present invention, componentsdesignated with the same reference numerals as in FIG. 3 represent thesame or corresponding components.

In FIG. 1, an approximately annular pressure plate 12 is concentric overthe entire circumference around a center line O, and is covered by apress-formed clutch cover 16. The outer peripheral part of the clutchcover 16 is connected to a flywheel 10. The clutch cover 16 is alsoformed into an approximately annular shape concentric secutive over theentire circumference.

A diaphragm spring 30 is disposed at a rear side (an arrow F indicatinga front side) of the flywheel 10. Pin 32 fits in a notch 31 extendingradially from an inner peripheral part of the diaphragm spring 30 andlocks diaphram spring 30 from rotative movement of the diaphragm spring30. The pin 32 is secured to an inner peripheral part of the clutchcover 16. An outer peripheral edge 33 of the diaphragm spring 30compressively contacts with the entire circumference of an incliningsurface 34 of the clutch cover 16. The inclining surface 34 is adaptedto stop a reaction force Q of the diaphragm spring 30. The incliningsurface 34 is formed into a conical surface which inclines toward thefront side as it approaches a radially inner part of the clutch cover 16toward a radially inner side.

An inner peripheral part 35 of the diaphragm spring 30 contactscompressively with a release bearing 24 (FIG. 3). Spring force P of thediaphragm spring 30 is released by pushing the inner peripheral part 35forward, in the direction of arrow F to a position 24a and is awellknown structure.

A lever 40 is disposed at each of four circumferential places, forexample, with equal distances left therebetween, in the circumferentialdirection of the clutch cover 16. Each lever 40 is carried by a shaft 41in a freely rotatable manner. The shaft 41 extending in a directionnormal to a plane of FIG. 1 and is supported by two lips 42 at itsopposite ends. Namely, one end of the shaft 41 is supported by theillustrated lip 42, and the other end of the shaft 41 is supported by asecond lip 42 (not illustrated).

The lip 42 is formed by cutting and raising upright a part of the clutchcover 16, having a hole 43 in the clutch cover 16. A fulcrum land 45,integral with the pressure plate 12, projects through hole 43 toward anoutside of the clutch cover 16.

An inside projection 44 is formed on a radially inner peripheral part ofthe diaphragm spring 30, i.e. an upper part thereof in FIG. 1, and theinside projection 44 contacts compressively with the diaphragm spring30. An outside projection 46 is formed at a bottom part of the lever 40,and the outside projection 46 contacts compressively with the fulcrumland 45 of the pressure plate 12.

The distance A between the center 01 of the shaft 41 and the insideprojection 44 is set longer than a distance B between the center 01 andthe outside projection 46. Thus, the lever ratio of the lever betweenprojection 44 and the center of shaft 41 is larger than the leverbetween center 01 of shaft 41 and outside projection 46. Accordingly, aspring force P of the diaphragm spring 30 acting on the insideprojection 44 is multiplied by a lever ratio A:B for transmission fromthe outside projection 46 to the fulcrum land 45 as a spring force W.

Therefore, the outer peripheral edge 33 is separated from the insideprojection 44 by a distance d, and an effective radius of the diaphragmspring 30 becomes c.

One end of a strap plate 50 extending in the circumferential directionof the clutch, i.e. normal to the plane, is fastened by a rivet 52 to anouter peripheral part of the pressure plate 12, and the other end of thestrap plate 50 is fastened to the clutch cover 16. Consequently, under areleased state where the spring force W from the inside projection 44 isremoved, the pressure plate 12 is adapted to be pulled back by a springforce of the strap plate 50.

Function will be described hereinunder. Under a clutch engaged state asillustrated by FIG. 1, the reaction force Q of the diaphragm spring 30is stopped by the inclining surface 34 of the clutch cover 16 and thespring force P is made act on the inside projection 44 of the lever 40.The spring force P is multiplied up to the spring force W by the leverratio A:B of the lever 40 to be transmitted to the fulcrum land 45 ofthe pressure plate 12.

At the time of clutch released state, where the release bearing 24 ismoved to the position 24a, the inner peripheral part 35 of the diaphragmspring 30 is pushed forward to prevent the spring force P of thediaphragm spring 30 from being produced, so that the diaphragm spring 30leaves the inside projection 44. In this state, the spring force Wtransmitted to the fulcrum land 45 is naturally removed and a pressingforce of the pressure plate 12 for pushing the clutch disc 14 toward theflywheel 10 does not function, so that the pressure plate 12 is pulledback by the spring force of the strap plate 50. Therefore, the clutchengaged state where the clutch disc 14 is sandwiched between theflywheel 10 and the pressure plate 12, is released.

Because the diaphragm spring 30 is disposed at the outside of the clutchcover 16, the diaphragm spring 30 is cooled by an outside air ofcomparatively low temperature and thermal influence is overcome.

The outer peripheral edge 33 of the diaphragm spring 30 is supported bythe inclining surface 34 so that the fulcrum of the diaphragm spring 30is shifted toward the radial outside of the clutch cover 16 as comparedwith FIG. 3 wherein the reaction force Q is supported by the most innerperipheral edge of the clutch cover 16. Therefore, the deflection isreduced, which is produced by the reaction force Q of the pressure plate12 secured to the flywheel 10 at its outer peripheral part.Consequently, the forward displacement of the inside projection 44 atthe time of releasing clutch is increased to provide a better so-calledclutch disengagement efficiency (release efficiency) as compared withthe conventional arrangement.

The lever 40 is not swung directly by the release bearing 24 as in theconventional arrangement but it is required only to transmit the springforce of the diaphragm spring 30 to the fulcrum land so that the leverratio A:B can be set large. Accordingly, the large effective springforce W can be produced from the small force P. Further, a releasingload of the release bearing 24, i.e. the depression force of a clutchpedal, is small.

Because axial thickness of the lever 40 is small and the outerperipheral edge 33 of the diaphragm spring 30 compressively contactswith the forwardly slanting inclining surface 34 of the clutch cover 16,the axial dimension of the entire clutch is small and a compact designof clutch is accomplished.

(2) Second embodiment

In FIG. 2 showing a second embodiment of the automobile clutch accordingto the present invention, the diaphragm spring 30 is locked its rotativemovement by a bracket 60. The bracket 60 is an annular member concentricover the entire circumference of clutch and has an annular projection 62compressively contacting with the diaphragm spring 30 and a claw 64projecting at a position corresponding to the notch 31.

Further, as illustrated in enlarged view FIG. 2a, a spacer 66 may beinstalled on an end face of the fulcrum land 45 with which the outsideprojection 46 of the lever 40 contacts, so that a height of the outsideprojection 46 may be adjusted by a thickness of the spacer 66.

Furthermore, as illustrated in enlarged FIG. 2b, a ring 70 concentricover the entire circumference of clutch may be interposed between theouter peripheral edge 33 of the diaphragm spring 30 and the incliningsurface 34.

EFFECT OF THE INVENTION

As described above, in the clutch cover assembly according to thepresent invention; the spring member is composed of the diaphragm spring30 exerting its spring force P in a direction opposite to the pressureplate; the clutch cover supports the outer peripheral part of thediaphragm spring 30 to form the fulcrum (the outer peripheral edge 33,for example) for stopping the reaction spring force Q of the diaphragmspring 30; the lever 40 for multiplying the spring force carried by theclutch cover 16 around the rotation center located at the positionradially inner than the spring force transmitting part (the fulcrum land45, for example) of the pressure plate 12, is disposed in the radialdirection; the radially inner side spring force action point (the insideprojection 44, for example) of the lever 40 is provided at a positionradially inner than said outer peripheral edge 33 of the diaphragmspring 30; the radially outer side spring force action point (theoutside projection 46) of the lever 40 is provided at the position tocause the distance B between the rotation center 01 of the lever 40 andthe outer side spring force action point to be shorter than the distanceA between said rotation center 01 and the inner side spring force actionpoint; and the lever 40 multiplies the spring force P of the diaphragmspring 30. Accordingly, the following effects become obtainable.

Because the diaphragm spring 30 is disposed at the outside of the clutchcover 16, the diaphragm spring 30 is cooled by the outside air ofcomparatively low temperature and hard to undergo the thermal influenceso that a service life of the diaphragm spring can be prolonged.

The outer peripheral edge 33 of the diaphragm spring 30 is supported bythe inclining surface 34 so that the fulcrum for the diaphragm spring 30is shifted toward the radial outside of the clutch cover 16 as comparedwith FIG. 3 wherein the reaction force Q is supported by the most innerperipheral edge of the clutch cover 16. Therefore, the deflection isreduced, which is produced by the reaction force Q of the pressure plate12 secured to the flywheel 10 at its outer peripheral part.Consequently, the forward displacement of the inside projection 44 atthe time of releasing clutch is increased to provide a better so-calledclutch disengagement efficiency (release efficiency) as compared withthe conventional case.

The lever 40 is not swung directly by the release bearing 24 as in theconventional embodiment, but it is required only to transmit the springforce of the diaphragm spring 30 to the fulcrum land 45 so that thelever ratio A:B can be set large. Accordingly, the large spring force Wcan be produced from the small spring force P. Further, the releasingload of the release bearing 24, i.e. the treading force of the clutchpedal can be minimized.

Since the axial thickness of the lever 40 becomes small and the outerperipheral edge 33 of the diaphragm spring 30 compressively contactswith the forwardly slanting inclining surface 34 of the clutch cover 16,the axial dimension of the entire clutch becomes small and a compactdesign of the clutch is accomplished.

What is claimed is:
 1. A clutch cover assembly having an approximatelyannular disc-like spring member disposed at an outside of a clutch covercovering a pressure plate; characterized by that the spring member is adiaphragm spring for exerting spring force on said pressure plate; saidclutch cover supporting an outer peripheral part of said diaphragmspring and forming a fulcrum for said diaphragm spring; a leverpivotally mounted on said clutch cover about a rotation center locatedat a position radially inward from a spring force transmitting part ofsaid pressure plate; a radially inner side spring force action point onsaid lever contacting said diaphgram spring at a position radiallyinward from said fulcrum of said diaphragm spring; a radially outer sidespring force action point on said lever contacting said spring forcetransmitting part of said pressure plate; a distance between therotation center of the lever and the outer side spring force actionpoint being shorter than a distance between said rotation center and theinner side spring force action point; said lever multiplying the springforce of said diaphragm spring and applying said multiplied spring forceto said pressure plate.
 2. A clutch cover assembly as set forth in claim1, in which an outer peripheral edge of said diaphragm springcompressively contacts an inclining surface of a radially intermediatepart of said clutch cover, and said inclining surface is formed into aconical surface which inclines toward a radially inner part of saidclutch cover.
 3. A clutch cover assembly as set forth in claim 1, inwhich said diaphragm spring has a notch extending radially from an innerperipheral part of said diaphragm spring, and a pin fitted in an innerperipheral part of said clutch cover is fitted into said notch.
 4. Aclutch cover assembly as set forth in claim 1, in which said diaphragmspring is locked from rotatable movement relative to said cover by aclaw of an annular bracket secured to a radially inner peripheral sideend of said lever, and a projection compressively contacting with saiddiaphragm spring concentrically over the entire circumference of saidclutch cover is formed on said bracket.
 5. A clutch cover assembly asset forth in claim 1, in which a spacer is interposed between an outsideprojection of said lever and said spring force transmitting part of saidpressure plate.
 6. A clutch cover assembly as set forth in claim 1, inwhich a ring concentric over the entire circumference of said clutchcover is interposed between an outer peripheral edge of said diaphragmspring and said clutch cover.
 7. A clutch cover assembly having anapproximately annular disc-like spring member disposed at an outside ofa clutch cover (16) covering a pressure plate (12); characterized bythat said spring member is a diaphragm spring (30) for applying a springforce to said pressure plate (12); the clutch cover (16) supporting anouter peripheral part of said diaphragm spring (30) and forming afulcrum (33) for said diaphragm spring (30); a lever (40) formultiplying the spring force of said diaphragm spring applied to saidpressure plate and pivotally mounted on the clutch cover (16) around arotation center (01) located at a position radially inward from a springforce transmitting part (45) of said pressure plate (12); a radiallyinner side spring force action point (44) on said lever (40) contactingsaid diaphragm spring at a position radially inward from said fulcrum(33) of said diaphragm spring (30); a radially outer side spring forceaction point (44) of said lever (40) contacting said spring forcetransmitting part of said pressure plate; a distance (B) between saidrotation center (01) of said lever (40) and said outer side spring forceaction point (46) being less than a distance (A) between said rotationcenter (01) and said inner side spring force action point (44); an outerperipheral edge of said diaphragm spring (30) being in compressivecontact with an inclining surface (34) of a radially intermediate partof said clutch cover (16); said inclining surface (34) being formed intoa conical surface which inclines toward a radially inner part of saidclutch cover; said diaphragm spring (30) having a notch (31) extendingradially from an inner peripheral part of said diaphragm spring; a pin(32) fitted in an inner peripheral part of the clutch cover extendingthrough said notch; a shaft (41) for carrying said lever (40); saidshaft (41) being supported by lips (42) formed by raised upright partsof said clutch cover (16); and said spring force transmitting part (45)of said pressure plate (12) passing through hole (43) in said clutchcover (16) formed by said lips (42).